1. Field of the Invention
This invention relates to an improvement in a method of making a rotor of an inductor type alternating current generator.
2. Discussion of Background
FIG. 13 is a sectional diagram showing a conventional inductor type alternating current generator shown, for instance, in Japanese Examined Patent Publication No. 1577/1992. In FIG. 13, reference numeral 1 designates a pulley, 2, a shaft connected to the pulley 1, and 3, a rotor fixed to the shaft 2. In the rotor 3, notation 3a designates first claws composing a first inductor, 3b, second claws composing a second inductor, 3c, a nonmagnetic ring and 3d, a core. Reference numeral 4 designates a front bracket, and 5, a rear bracket, both of which rotatably support the shaft 2 through bearings 6 and 7. Numeral 8 designates an excitation coil fixed to the rear bracket 5 through the core 9, 10, a stator fixed between the front bracket 4 and the rear bracket 5, and 10a, a stator coil. Numeral 11 designates a rectifier fixed to the rear bracket 5 and connected to the stator coil 10a, 12, a regulator fixed to the rear bracket 5 and connected to the excitation coil 8, and 13, a rotating fan fixed to the shaft 2 along with the pulley 1.
The pulley 1 is driven to rotate by a prime mover, not shown, through a belt, by which the rotor 3 fixed to the shaft 2 is rotated. The first claws 3a and the second claws 3b of the rotor 3 are inductors excited by the excitation coil 8 in different polarities, which are alternately and opposedly disposed and which are connected and fixed to the nonmagnetic ring 3c.
An excited electromotive force is generated in the stator coil 10a when the rotor 3 is rotated and crosses a magnetic field generated by the excitation coil 8. This excited electromotive force generates a three-phase alternating current, which is full-wave-rectified into a direct current by the rectifier 11 and the direct current is supplied to a battery or an electric load. The regulator 12 controls a current flowing in the excitation coil 8 to maintain the electromotive force excited in the stator coil 10a at a constant voltage. The front bracket 4 and the rear bracket 5 compose an outer frame of the generator, which is attached and fixed to the prime mover. The fan 13 rotates along with the pulley 1 and cools the inside of the generator.
In the conventional inductor type rotor constructed as above, an electron beam welding device is employed as a means for connecting and fixing the first and second claws 3a and 3b and the nonmagnetic ring 3c.
As shown in FIGS. 14(a), 14(b) and 15, in the electron beam welding device, an electron beam is directly irradiated to contact faces of the first claws 3a or the second claws 3b and the nonmagnetic ring 3c, from distal ends of the first claws 3a or the second claws 3b along an axial direction, to thereby weld and connect the first claws 3a, the second claws 3b and the nonmagnetic ring 3c.
In the conventional method of welding by an electron beam device, the electron beam is irradiated from the distal end sides of the first claws 3a or the second claws 3b along the axial direction to thereby perform welding. Accordingly, the direction of irradiation of the electron beam differs among the first claws 3a and the second claws 3b. After the welding of the first claws 3a of one inductor and the nonmagnetic ring 3c has been finished, the direction of opening of the rotor is reversed by 180.degree. and the second claws 3b of the other inductor and the nonmagnetic ring 3c are welded by irradiating again the electron beam from the same direction, whereby the welding operation is complicated and the operational performance is poor.